Bureau of Meteorology (BoM) Data

Listing of all BoM tropical cyclones : this includes all tropical cyclones tracked by the BoM since the 1906/07 season. Historical data is reviewed once updated best track data becomes available.

Joint Typhoon Warning Center (JTWC) Data

Australian Region (AU): 90E to 180E (this is a best fit region and not an official TC basin)
South Indian Ocean (SIO): 15E to 135E
South Pacific Ocean (SPAC): 135E to 110W
Southern Hemisphere (SH): 15E to 110W

Listing of all JTWC tropical cyclones : this includes all tropical cyclones in the JTWC best track dataset since the 1944/45 season. Annual data for the past year is typically released in March or April.

Operational (OPER) Data

Australian Region (AU): 90E to 180E (this is a best fit region and not an official TC basin)
South Indian Ocean (SIO): 15E to 135E
South Pacific Ocean (SPAC): 135E to 110W
Southern Hemisphere (SH): 15E to 110W

Listing of all operational storms : this includes all tropical cyclones, tropical lows, tropical depressions and hybrid lows tracked by the various tropical cyclone warning agencies since the 1997/98 season. Tracks are typically updated monthly.

Tropical Cyclone Map Intensity Scale Information

The definitions in the following table are from the Southern Hemisphere classification system (as used by the Australian BoM), and all maps on this website have been plotted using it. JTWC best track data has been converted from 1-minute average winds in knots, to the Southern Hemisphere standard of 10-minute average winds in knots, then converted to km/h. The conversion used is "JTWC 1-min" * 0.88 * 1.852. Operational data is also converted using this formula where 10-min average winds are not available.

The Hurricane and Typhoon classification systems are different.

Storm Type

Pressure (hPa)

Max Gusts (km/h)

10-min Ave Winds (km/h)

Dvorak Rating

Effects during landfall

Tropical Low

>= 996

< 63

2.0 - 2.5

Category 1 Tropical Cyclone

986 - 995

< 125

63 - 88

3.0 - 3.5

Negligible house damage. Damage to some crops, trees and caravans.

Category 2 Tropical Cyclone

971 - 985

125 - 164

89 - 117

4.0 - 4.5

Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small craft may break moorings.

Category 3 Tropical Cyclone

956 - 970

165 - 224

118 - 159

5.0 - 5.5

Some roof and structural damage. Some caravans destroyed. Power failures likely.

A comparison between the Australian Tropical Cyclone Intensity Scale and the
Saffin/Simpson Hurricane Intensity Scale

Both the U. S. National Weather Service and Australia's Bureau of
Meteorology (BoM) employ a 5-point scale by which to alert the public
of the general effects which can be expected from tropical cyclones of
varying intensities. In both systems tropical cyclones are classified
from Category 1 (the weakest) to Category 5 (the strongest), and each
scale seems to have been adopted enthusiastically by the general public
in both Australia and in the United States.

However, the scales are very different in their conception and in the
boundaries between their respective categories. The Saffir/Simpson
scale, used in the United States, is used for classifying tropical
cyclones which have reached hurricane intensity while the Australian
scale is utilized for all tropical cyclones of gale intensity or higher.
Nowadays, anyone anywhere in the world with internet access can follow
tropical cyclones in great detail, and there are many persons who delight
in tracking and discussing storms in all oceanic basins. Considerable
confusion has sometimes arisen when, for example, someone in the U. S.
is following an Australian cyclone and assuming that the category given
in the BoM warnings (and often aired in the international news media)
is equivalent to its Saffir/Simpson category.

The following chart summarizes the salient characteristics of the
two scales:

Characteristic

Saffir/Simpson

Australian

Beginning Point

Hurricane force

Gale force

Wind Parameter

Sustained wind (1-min avg)

Peak gusts

Wind Velocity Units

Statute miles-per-hour

Kilometres-per-hour

My purpose here is to provide information whereby persons interested
in comparing the two scales can easily do so. Table 1 defines the
Saffir/Simpson Scale in terms of the 1-min avg maximum sustained wind
(MSW) in statute miles-per-hour (mph) while Table 2 defines the
Australian Cyclone Severity Scale in terms of peak wind gusts in
kilometres-per-hour (km/hr). I have not included the narrative
describing the degree and type of damage which can be expected with
each category in both scales. Also, in both tables I have included
the qualifying wind velocity in nautical miles-per-hour (kts) along
with the nominal central pressure range in millibars (mb)--numerically
equal to hectopascals (hPa).

Table 1 - Saffir/Simpson Scale

Category S/S

1-min avg MSW (mph)

1-min avg MSW (kts)

Central Pressure (mb)

1

74 - 95

64 - 82

>= 980

2

96 - 110

83 - 95

965 - 979

3

111 - 130

96 - 113

945 - 964

4

131 - 155

114 - 135

920 - 944

5

>= 156

>= 136

<= 919

Table 2 - Australian Cyclone Severity Scale

Category Aust

Peak gusts (km/hr)

Peak gusts (kts)

Central Pressure (hPa)

1

90 - 124

49 - 67

986 - 995

2

125 - 169

68 - 91

971 - 985

3

170 - 224

92 - 121

956 - 970

4

225 - 279

122 - 150

930 - 955

5

>= 280

>= 151

<= 929

The following two tables define each scale in terms of the other
scale's parameters, i.e., the Saffir/Simpson scale is defined in terms
of a 10-min avg MSW in kts, and peak gusts in kts and in km/hr (Table 3)
while the Australian scale is defined in terms of a 10-min avg MSW in
kts and a 1-min avg MSW in mph (Table 4).

Finally, as an additional aid to comparison, I have included a
table (Table 5) comparing each cyclone scale with the Dvorak scale,
used extensively in estimating tropical cyclone intensity from visible
and infrared satellite imagery. I have started the table with T2.0
since neither TPC/NHC nor the BoM TCWCs routinely issue advisories/
advices/warnings for systems less than that Dvorak rating. (See the
key following the table for an explanation of the abbreviations used.)